CN101287927B - dynamic shock absorber - Google Patents

Abstract

The invention provides a dynamic vibration absorber, wherein the inner diameter (D2) of a first hole portion (32) formed at one axial end of a main body (24) overlapping a mass portion (26) in the radial direction is set smaller than the inner diameter D3(D3 > D2) of a second hole portion (34) formed at the other axial end of the main body (24) not overlapping the mass portion (26) in the radial direction and fastened with a band member (20). An outer diameter (D1) of a drive shaft (12) to be press-fitted into the first hole portion and the second hole portion is set to be larger than an inner diameter (D2) of the first hole portion (32) and larger than an inner diameter (D3) of the second hole portion (34) (D1 > D3 > D2).

Description

dynamic shock absorber

technical field

The present invention relates to a dynamic shock absorber mounted on a rotating shaft such as a drive shaft of an automobile for attenuating harmful vibrations generated on the rotating shaft. the

Background technique

Hitherto, there are known dynamic dampers installed on a rotating shaft such as a drive shaft or a propeller shaft of an automobile for attenuating undesired harmful vibrations due to unbalanced rotation conditions caused when the rotating shaft rotates, For example, bending vibration, torsional vibration, etc. the

When the natural frequency of the dynamic shock absorber is equal to the main frequency of the excited harmful vibration of the rotating shaft, the vibration energy of the rotating shaft is converted into the vibration energy of the dynamic shock absorber through resonance, so that it has the function of absorbing the vibration energy of the rotating shaft . the

For example, a dynamic shock absorber of the above-mentioned type is disclosed in Patent Document 1, which includes: a boss having a central hole in which a rotating shaft such as a drive shaft is press-fitted; An annular weight (mass part); an elastic connector for radially connecting the boss and the weight; and a fixing band fastened on the outer peripheral surface of the boss to fix the boss to the rotating shaft. the

Further, the dynamic shock absorber disclosed in Patent Document 2 includes a boss having locking grooves at both axial ends, an annular mass portion arranged around the boss, and a fixing band wound on the locking grooves to fix the boss. the

However, the dynamic shock absorbers disclosed in Patent Documents 1 and 2 are disadvantageous in that water can penetrate into the gap between the rotating shaft and the inner wall surface of the boss at the portion where the fixing band is not fastened to the boss. . the

Dynamic shock absorbers mounted on rotating shafts such as drive shafts or propeller shafts are typically used in harsh air environments close to the ground. When the dynamic damper is used in such an environment for a long period of time, the material such as rubber fatigues, so that its fastening force on the rotating shaft decreases. As a result, water can penetrate into the gap between the rotating shaft and the inner wall of the boss at the portion where the fixing band is not fastened to the boss. the

The above problems can be solved by reducing the inner diameter of the boss to improve the contact between the inner wall surface of the boss and the outer peripheral surface of the rotating shaft. In this case, however, an increased force is required to press-fit the rotating shaft into the boss against the inner wall surface of the boss when mounting the dynamic damper on the rotating shaft. Therefore, work efficiency is lowered, and an additional press-fitting device or the like is required in addition to the existing equipment, making the manufacturing cost higher. the

Furthermore, when an increased force is applied to press fit the rotary shaft into the boss against the inner wall surface of the boss, the inner wall of the boss is overstressed and deformed. Specifically, in the boss, the portion to be fastened by the fixing band is thinner than the other portion, so as to deform and extend in the direction of pressing the rotation axis. the

Patent Document 1: Japanese Laid-Open Publication No.59-003041

Patent Document 2: Japanese Laid-Open Patent Publication No.02-154827

Contents of the invention

A general object of the present invention is to provide a dynamic shock absorber which prevents external water or the like from penetrating thereinto. the

The main object of the present invention is to provide a dynamic shock absorber which can be more efficiently mounted on a rotating shaft. the

In the dynamic shock absorber of the present invention, the through hole formed in the main body has an inner diameter D2 at an axial end overlapping the mass part in the radial direction, and the inner diameter D2 is smaller than the rotation diameter to be press-fitted in the through hole. Shaft outer diameter D1. Therefore, the inner wall surface of the through hole having the inner diameter D2 can sufficiently contact the outer peripheral surface of the rotating shaft at the one end, so that the penetration of water between the surfaces can be effectively prevented. the

Furthermore, in the present invention, the through hole formed in the main body has an inner diameter D3 at the other axial end that does not radially overlap with the mass portion, which is larger than the inner diameter D2 at the one end where the main body The vicinity of the other end is thin-walled, and a belt is fastened to the thin-walled portion. Therefore, the through hole having an inner diameter D3 can sufficiently contact the outer peripheral surface of the rotating shaft at the other end as at the one end, so that penetration of water can be effectively prevented. the

Therefore, in the present invention, the main body can be ideally contacted with the rotating shaft at both the one axial end and the other axial end, thereby preventing water from passing through the through hole in the main body at both ends. The gap between the inner wall and the outer peripheral surface of the rotating shaft penetrates. the

In the present invention, the rotation shaft is press-fitted in the through hole of the main body at the thick-walled portion of the main body near the one axial end and at the thin-walled portion of the main body near the other axial end. The required force is different, and the elastic deformation of the main body is different at a portion near the one axial end and at a portion near the other axial end. That is, elastic deformation and press-fit force are large at one end of the main body overlapping the mass portion, and small elastic deformation and press-fit force at the other thin-walled end of the main body that does not overlap the mass portion. the

Therefore, in the present invention, the installation of the rotation shaft along the main body can be improved, and deformation of the thin-walled portion can be prevented, so that the performance of the dynamic shock absorber can be prevented from being deteriorated. the

Furthermore, in the present invention, it is preferable that the rotation shaft is press-fitted in the through hole from the one end having the inner diameter D2 to the other end having the inner diameter D3. In this case, it is possible to achieve a gap between the rotating shaft and the first hole portion having a small inner diameter near the one end and between the rotating shaft and the hole portion near the other end having a larger inner diameter and to which the belt is fastened. The tight seal between the second hole portions can effectively prevent water penetration at both ends. the

Description of drawings

1 is a vertical sectional view of a driving force transmission mechanism incorporating a dynamic shock absorber according to an embodiment of the present invention, some parts are omitted in the view;

Fig. 2 is the enlarged vertical sectional view of the dynamic shock absorber of the driving force transmission mechanism;

Fig. 3 is a side view of a dynamic shock absorber according to an embodiment of the present invention;

Fig. 4 is a vertical sectional view taken along line IV-IV of Fig. 3;

Fig. 5 is a partially enlarged vertical sectional view of a dynamic shock absorber according to another embodiment of the present invention, in which a drive shaft is not pressed;

Fig. 6 is a partial enlarged vertical sectional view of the dynamic shock absorber of Fig. 5, and the middle pressure of the dynamic shock absorber is equipped with a drive shaft;

Fig. 7 is a partially enlarged vertical sectional view of a dynamic shock absorber according to a comparative embodiment, in which a drive shaft is not pressed;

Fig. 8 is a partially enlarged vertical sectional view of the dynamic shock absorber of Fig. 7, and the middle pressure of the dynamic shock absorber is equipped with a drive shaft;

Fig. 9 is a vertical sectional view along the axial direction of a dynamic shock absorber according to yet another embodiment of the present invention;

Fig. 10 is a vertical sectional view of the dynamic shock absorber of Fig. 9, and the middle pressure of the dynamic shock absorber is equipped with a drive shaft;

Fig. 11 is a vertical sectional view along the axial direction of a dynamic shock absorber according to a modified example of the dynamic shock absorber of Fig. 9; and

Fig. 12 is a vertical sectional view of the dynamic shock absorber of Fig. 11, which is fitted with a drive shaft. the

Detailed ways

Fig. 1 is a vertical sectional view of a driving force transmission mechanism, some parts are omitted in the view, wherein a dynamic shock absorber according to one embodiment of the present invention is mounted on a drive shaft as a rotating shaft, and Fig. 2 is mounted on a drive shaft An enlarged vertical section view of a dynamic shock absorber. the

The driving force transmission mechanism 10 includes: a drive shaft 12 having an outer diameter D1 as shown in FIG. 2 ; and a Birfield type constant velocity joint 14 and a tripod type constant velocity joint coupled to respective ends of the drive shaft 12 16. Joint covers 18, 19 made of rubber or resin are attached to the Birfield type constant velocity joint 14 and the tripod type constant velocity joint 16, respectively. A dynamic shock absorber 22 is mounted approximately at the center of the drive shaft 12 by a band 20 such as a stainless steel band. the

As shown in FIGS. 3 and 4 , the dynamic shock absorber 22 has: a substantially cylindrical main body 24 surrounding the outer peripheral surface of the drive shaft 12 ; a single annular mass portion 26 arranged radially outside the main body 24 , Located near one axial end of the main body 24 ; an annular connection support part 28 , which connects the main body 24 and the mass part 26 . the

The main body 24, the connecting support part 28 and the mass part 26 are integrally molded to form a one-piece flexible piece made of rubber material. the

The main body 24 has a through hole 30 extending in the axial direction, and the drive shaft 12 is press-fitted in the through hole 30 . The through hole 30 has a first hole portion 32 with an inner diameter D2 , a second hole portion 34 with an inner diameter D3 , and a tapered portion 36 . The first hole portion 32 is formed at the one axial end of the main body 24 that overlaps the mass portion 26, and the second hole portion 34 is formed at the other axial end that does not overlap the mass portion 26 in the radial direction. The portion 36 is formed between the first hole portion 32 and the second hole portion 34 and does not overlap the mass portion 26 in the radial direction. the

In this embodiment, the tapered portion 36 is formed such that the inner diameter gradually decreases from the second hole portion 34 toward the first hole portion 32 . As shown in FIG. 4, the large-diameter starting end 36a of the tapered portion 36 substantially corresponds to the side wall 38a (described later) of the annular recess 38 formed on the outer peripheral surface of the main body 24 in the radial direction, and the tapered portion 36 The small-diameter terminal end 36b of the substantially corresponds to the side wall 26a of the mass part 26 in the radial direction. the

Preferably, the starting end 36a is located at a position substantially corresponding to the sidewall 38a of the annular recess 38 in the radial direction, or at a position closer to the connecting support portion 28 in the radial direction without overlapping with the annular recess 38 . When the body 24 has a varying radial thickness at the annular recess 38 and the strap 20 is fastened on the annular recess 38, the body 24 may elastically deform and warp non-uniformly. In this case, the main body 24 is unevenly subjected to the fastening stress of the belt 20, so that water penetration cannot be prevented. the

Preferably, the terminal end 36b is located at a position closer to the annular recess 38 in the radial direction without overlapping the connection support portion 28 . When the main body 24 has a varying radial thickness at the connection support portion 28, the main body 24 may elastically deform and warp unevenly. In this case, a predetermined spring constant cannot be obtained, so that a desired damping function of the drive shaft 12 cannot be obtained. the

In this embodiment, the tapered portion 36 is formed between the first hole portion 32 having the uniform inner diameter D2 and the second hole portion having the uniform inner diameter D3, although this is not limitative. An R portion or a stepped portion having a predetermined radius of curvature may be formed instead of the tapered portion 36 . the

An annular recess 38 on which the belt 20 such as a stainless steel belt is wound is formed on the outer peripheral surface of the main body 24 near the other axial end that does not overlap the mass portion 26 in the radial direction. When the belt 20 is fastened on the annular recess 38 , the dynamic shock absorber 22 is fixed at a predetermined position on the drive shaft 12 . the

The length of the second hole portion 34 in the axial direction of the main body 24 is preferably larger than the width of the belt 20 (the length of the belt 20 in the axial direction of the main body 24 ). the

The connection support part 28 is formed between the mass part 26 of the outer periphery and the main body 24 of the inner periphery. Five connection support portions 28 protrude radially outward from the outer surface of the main body 24 at equal intervals in the circumferential direction. The connecting supports 28 consist of a flexible rubber material, which elastically support the mass part 26 by virtue of their flexibility. the

A rubber film 40 is formed between every two adjacent connection support parts 28, which is integrated with the connection support parts 28 and is located radially inside the mass part 26. A thick rubber stopper portion 42 protruding radially inward is formed integrally with the rubber membrane 40 positioned between every two adjacent connection support portions 28 . The rubber stopper 42 may be in contact with the outer peripheral surface of the main body 24 so as to prevent the excessive displacement of the mass part 26 toward the main body 24 in the radial direction. the

An annular space 44 having a substantially triangular cross-sectional shape in which an annular weight 46 having a chamfered triangular cross-sectional shape is placed is formed in the annular mass portion 26 . In this embodiment, when the drive shaft 12 vibrates, the weight 46 is displaced in the radial compression/tension direction integrally with the mass portion 26 . the

The weight 46 may comprise a sintered body made by sintering tungsten alloy powder together with a metal binder. Instead of a sintered body, a molded body produced by metal injection molding (MIM) or powder injection molding (PIM) can be used. The weight 46 thus obtained generally has a specific gravity greater than 14, for example a high specific gravity above 17, and therefore has a large weight. the

Preferred examples of tungsten alloys include W-1.8Ni-1.2Cu (the specific gravity is 18.5, each number before the element symbol indicates the weight % ratio, and the same is true for the following examples), W-3.0Ni-2.0Cu (the specific gravity is 17.8), W-5.0Ni-2.0Fe (specific gravity: 17.4) and W-3.5Ni-1.5Fe (specific gravity: 17.6). The specific gravity of the weight 46 made of tungsten alloy is more than twice that of the weight made of iron material. If the mass of the weight 46 is the same as that of the iron material, the volume of the weight 46 is about 1/3 to 1/2 of these weights. the

In other words, if the weight 46 is made of tungsten alloy, its size is much smaller than the traditional weight made of iron material. the

The relationship between the outer diameter D1 of the drive shaft 12 and the inner diameter D2 of the first hole portion 32 and the inner diameter D3 of the second hole portion 34 of the through hole 30 formed in the main body 24 will be described below. the

The first hole portion 32 is formed at the one axial end of the main body 24 radially overlapping the mass portion 26 . The inner diameter D2 of the first hole portion 32 is smaller than the outer diameter D1 of the drive shaft 12 to be press-fitted in the first hole portion 32 ( D1 > D2 ). the

Further, a second hole portion 34 is formed at the other axial end of the main body 24 not overlapping the mass portion 26 in the radial direction, and the band 20 is fastened on the annular recess 38 . The inner diameter D3 of the second hole portion 34 is larger than the inner diameter D2 of the first hole portion 32 formed at the one axial end of the main body 24 and smaller than the outer diameter D1 of the drive shaft 12 ( D1 > D3 > D2 ). the

Not only the dynamic shock absorber having one mass portion 26 shown in FIG. 4 satisfies the above relational expression, but also the dynamic shock absorber (not shown) having two or more mass portions according to the present invention satisfies the above relational expression . the

In this embodiment, in the main body 24 , the wall thickness of the one axial end having the first hole portion 32 is thicker than the wall thickness of the other axial end having the second hole portion 34 . the

The dynamic shock absorber 22 according to the embodiment of the present invention is basically constituted as described above. The operation and advantages of the dynamic shock absorber 22 will be described below. the

First, the drive shaft 12 is press-fitted into the first hole portion 32 of the through hole 30 in the main body 24 and inserted through the second hole portion 34 to a predetermined position. Next, the strap 20 is wrapped and secured over the annular recess 38 of the main body 24 . The dynamic shock absorber 22 is positioned and secured at a desired location on the drive shaft 12 . the

In the driving force transmission mechanism 10 mounted on a vehicle, the dynamic damper 22 is mounted on the drive shaft 12 as described above. When the drive shaft 12 vibrates for some reason, the mass portion 26 including the weight 46 is subjected to tension/compression deformation through the connection support portion 28 . the

Specifically, when the drive shaft 12 vibrates undesirably, the vibration is transmitted from the main body 24 to the mass portion 26 through the connection support portion 28 . The resonant frequency of the mass 26 containing the weight 46 is adapted to the frequency of the undesired vibrations. Thus, at this time, the mass portion 26 expands and contracts from the connection support portion 28 in the radial direction of the drive shaft 12 , that is, undergoes tension/compression deformation. the

The dynamic damper of the present invention is capable of shear deformation such that it is pulled in a direction opposite to the rotational direction of the drive shaft 12 along the circumferential direction of the drive shaft 12 (such a dynamic damper will be described below). Of course, the dynamic shock absorber may be a dynamic shock absorber subjected to both tension/compression deformation and shear deformation. the

The mass portion 26 resonates during tension/compression deformation and/or shear deformation. The mass portion 26 has approximately the same resonance frequency, and the vibration energy generated in the drive shaft 12 is absorbed by the connection support portion 28, thereby advantageously damping the vibration. Accordingly, the vibration of the drive shaft 12 is attenuated by the resonance of the mass portion 26 (weight 46 ) elastically supported by the flexible connection support portion 28 . the

In this embodiment, the first hole portion 32 is formed at the one axial end of the main body 24 that overlaps the mass portion 26 in the radial direction, and at the other axial end of the main body 24 that does not overlap the mass portion 26 in the radial direction. A second hole portion 34 is formed toward the end to which the band 20 is fastened, and the inner diameter D2 of the first hole portion 32 is smaller than the inner diameter D3 of the second hole portion 34 (D3>D2). Further, the outer diameter D1 of the drive shaft 12 to be press-fitted is larger than the inner diameter D2 of the first hole portion 32 and larger than the inner diameter D3 of the second hole portion 34 ( D1 > D3 > D2 ). the

Thus, in this embodiment, the inner diameter D2 of the first hole portion 32 formed at the one axial end of the main body 24 radially overlapping the mass portion 26 is smaller than the outer diameter D1 of the drive shaft 12 to be press-fitted. , so that the inner wall of the first hole portion 32 can be in sufficient contact with the outer peripheral surface of the drive shaft 12 so that water can be effectively prevented from penetrating between the surfaces. the

Also, in this embodiment, the inner diameter D3 of the second hole portion 34 is larger than the inner diameter D2 of the first hole portion 32 . The second hole portion 34 is formed at the other axial end of the main body 24 that does not radially overlap the mass portion 26 . The wall thickness of the main body 24 is thinner near the other end, and the belt 20 is fastened along the annular recess 38 formed on this thinner portion of the outer peripheral surface of the main body 24, so that, as at the one end of the main body 24, The through hole at the other end can fully contact the outer peripheral surface of the drive shaft 12, so that water penetration can be effectively prevented. the

Therefore, in this embodiment, both said one axial end and said other axial end of the main body 24 can be in good contact with the drive shaft 12, so that water can be prevented from passing through the through hole 30 at both ends. The gap between the inner wall of the drive shaft and the outer peripheral surface of the drive shaft 12 is infiltrated. the

Furthermore, in this embodiment, the force required to press-fit the drive shaft 12 into the through hole 30 of the main body 24 is at the thick-walled portion near the one axial end and at the thick-walled portion near the other axial end. The thin-walled portion is different, and the elastic deformation of the main body 24 is different at the first hole portion 32 and the second hole portion 34 of the through hole 30 in the main body 24 . That is, the elastic deformation and the press-fitting force are larger at the one end of the main body 24 overlapping the mass portion 26 (at the first hole portion 32 ), and are larger at the end of the main body 24 not overlapping the mass portion 26 . It is smaller at the other thin-walled end (at the second hole portion 34 ). the

Therefore, in this embodiment, the attachment of the drive shaft 12 to the main body 24 can be improved, and deformation of the thin-walled portion can be prevented, so that the performance of the dynamic shock absorber 22 can be prevented from being deteriorated. the

A dynamic shock absorber according to another embodiment of the present invention is shown in FIGS. 5 and 6 . The same components in the above-described embodiment and the following embodiments are denoted by the same reference numerals, and repeated description thereof will be omitted. the

The dynamic shock absorber 22a according to another embodiment can achieve the same effect as the dynamic shock absorber 22 according to the above embodiment, except that the starting end 36a of the tapered portion 36 is positioned closer to the one axial direction of the main body 24. end. the

The dynamic shock absorber 100 according to the comparative example shown in FIGS. 7 and 8 differs from the dynamic shock absorber 22 a according to the other embodiment in that the tapered portion 36 is closer to the opposite end. The tapered portion 36 is positioned closer to the other axial end of the main body 24 so that the portion elastically deformed by the fastening strap 20 overlaps the portion elastically deformed by press-fitting. Thus, when the strap 20 is fastened to the main body 24, the overlapping portion is disadvantageously warped. the

9 and 10 show a dynamic shock absorber 50 according to yet another embodiment of the present invention. the

The dynamic damper 50 according to this still further embodiment can effectively attenuate shear deformation that causes the dynamic damper 50 to be pulled in a direction opposite to the rotational direction of the drive shaft 12 along the circumferential direction of the drive shaft 12 . the

In the cylindrical body 52, a through hole 54 extends in the axial direction. The through hole 54 has a first hole portion 58 with an inner diameter D2 , a second hole portion 60 with an inner diameter D3 , a first tapered portion 62 , and a second tapered portion 64 . The mass portion 56 is arranged near one axial end of the main body 52 at which the first hole portion 58 is formed. The second hole portion 60 is formed at the other axial end that does not overlap the mass portion 56 in the radial direction. A first tapered portion 62 is formed on the inner wall of the main body 52 between the first hole portion 58 and the mass portion 56 , which does not overlap the mass portion 56 in the radial direction. On the main body 52 , a second tapered portion 64 is formed between the second hole portion 60 and the mass portion 56 , which does not overlap the mass portion 56 in the radial direction. A ring-shaped weight 68 having a rectangular cross-sectional shape is placed in the space 66 of the mass portion 56 . the

The first tapered portion 62 is formed such that the inner diameter gradually decreases from the mass portion 56 toward the first hole portion 58 in the axial direction. The second tapered portion 64 is formed such that the inner diameter gradually decreases from the mass portion 56 toward the second hole portion 60 in the axial direction. The inclination angle of the first tapered portion 62 is larger than the inclination angle of the second tapered portion 64 . the

At one end of the main body 52 connected to the mass part 56 disposed in the middle of the main body 52, the first elastic part 70a adjacent to the mass part 56 elastically supports the weight 68 in the shear direction, and the first elastic part 70a adjacent to the first elastic part 70a elastically supports the weight 68. A damper portion 72a has a substantially uniform outer diameter, and a thick-walled first fixing portion 74a adjacent to the first damper portion 72a has a first hole portion 58 with an inner diameter D2. the

At the other end of the main body 52 connected to the mass part 56 disposed in the middle of the main body 52, the second elastic part 70b adjacent to the mass part 56 elastically supports the weight 68 along the shearing direction, and the second elastic part 70b adjacent to the second elastic part 70b elastically supports the weight 68 along the shear direction. The second damping portion 72b is formed with an annular protrusion 75 on its outer peripheral surface, and the second fixing portion 74b adjacent to the second damping portion 72b is formed with an annular recess 38 on the outer peripheral surface and has an inner diameter of The second hole portion 60 of D3, the strap 20 is fastened on the annular recess 38 . The first elastic portion 70a and the second elastic portion 70b do not overlap the first fixing portion 74a and the second fixing portion 74b in the radial direction, respectively. the

In this embodiment, the first hole portion 58 is formed at an axial end of the main body 52 overlapping the mass portion 56 in the radial direction, and the inner diameter D2 of the first hole portion 58 is smaller than that to be press-fitted in the first hole portion. The outer diameter D1 of the drive shaft 12 in 58 (D1>D2). the

In addition, a second hole portion 60 is formed at the other axial end of the main body 52 that does not overlap the mass portion 56 in the radial direction, the band 20 is fastened to the annular recess 38 , and the inner diameter D3 of the second hole portion 60 is larger than that located at The inner diameter D2 of the first hole portion 58 at the one axial end is smaller than the outer diameter D1 of the drive shaft 12 (D1>D3>D2). the

The inner diameter D2 of the first fixing portion 74 a is preferably 80% to 85% of the outer diameter D1 of the drive shaft 12 . When the inner diameter D2 is less than 80% of the outer diameter D1, the first fixing portion 74a may be broken during the press-fit process of the drive shaft 12 from the first hole portion 58 in the main body 52 to the second hole portion 60, and the dynamic vibration damping The device 50 cannot be manually installed by the operator. On the other hand, when the inner diameter D2 is greater than 85% of the outer diameter D1, the contact between the first fixing portion 74a and the drive shaft 12 is weak, making it difficult to maintain a sufficient seal against water penetration. the

As shown in FIG. 10 , when the drive shaft 12 is press-fitted in the dynamic shock absorber 50 according to this still further embodiment, the inside of the mass portion 56 is separated from the outer surface of the drive shaft 12 in the radial direction, and A gap 76 is formed in the axial direction between the tapered portion 62 and the second tapered portion 64 . the

When the dynamic damper 50 is subjected to shear deformation, thereby pulling the dynamic damper 50 in a direction opposite to the rotational direction of the drive shaft 12 , the vibration of the drive shaft 12 is effectively damped by the gap 76 . In the dynamic shock absorber 50 according to this still further embodiment, as at the one end, the main body 52 is in sufficient contact with the outer peripheral surface of the drive shaft 12 at the other end, thereby being effective in the same manner as the above-mentioned embodiment. Prevent water penetration. the

In this still another embodiment, the drive shaft 12 goes from the first fixing portion 74a having the first hole portion 58 (which has a smaller inner diameter D2) to the second fixing portion 74a having the second hole portion 60 (which has a larger inner diameter D3). The second fixing portion 74 b is press-fitted in the main body 52 of the dynamic damper 50 so that the dynamic damper 50 is mounted (fixed) to a predetermined portion of the drive shaft 12 . the

In this embodiment, when the drive shaft 12 is inserted from the first hole portion 58 having the small inner diameter D2 , the first elastic portion 70 a is compressed and deformed in the axial direction of the main body 52 . When inserting the drive shaft 12 in the opposite direction from the second hole portion 60 of the main body 52 having a larger inner diameter D3 and pushing it through the second hole portion 60 to the first hole portion 58, due to the smaller inner diameter D2 When the drive shaft 12 is obstructed, the first elastic portion 70 a is stretched and deformed along the axial direction of the main body 52 (the direction in which the drive shaft 12 is pushed). the

The axial load applied to the first elastic portion 70 a is an important factor for setting the spring constant of the dynamic shock absorber 50 . It is assumed that the load of the above-mentioned tensile deformation is larger than the load of the above-mentioned compressive deformation, and the dynamic shock absorber 50 will be broken in the tensile deformation. In this yet another embodiment, it is preferable to protect the first elastic portion 70 a during the process of installing the dynamic shock absorber 50 to the drive shaft 12 , so that the yield of products can be improved. the

The dynamic shock absorber 50a of Fig. 11 and Fig. 12 is a modified example of the dynamic shock absorber 50 of Fig. 9 and Fig. 10 according to yet another embodiment of the present invention. The R portion 78 a and the second R portion 78 b replace the first tapered portion 62 and the second tapered portion 64 . The dynamic shock absorber 50a has the same advantageous effects as described above. the

Claims (5)

1. A dynamic shock absorber (22a) for attenuating the vibration of a rotating shaft (12), the dynamic shock absorber comprising: a generally cylindrical body (24) having a through hole (30) into which said rotating shaft (12) is press fitted; a mass (26) comprising a weight (46), arranged radially outside said body (24), near an axial end of said body (24); a flexible annular connection support portion (28) arranged between said body (24) and said mass portion (26); and a strap (20) fastened to a portion of said body (24) near the other axial end of said body (24), thereby securing said body (24) to said rotating shaft (12 ), said portion does not overlap with said quality portion (26) in the radial direction of said main body (24), Wherein, the through hole (30) has a first hole portion (32) and a second hole portion (34), the first hole portion (32) is formed on the outside of the main body (24) and the At one axial end of the quality portion (26), and the second hole portion (34) is formed at the other axial end of the main body (24), the outer side of the other axial end is not arranging said mass portion (26), The first hole portion (32) extends from an open end of the main body (24) in the axial direction of the main body (24) with a uniform inner diameter, The second hole portion (34) extends from the other open end of the main body (24) in the axial direction of the main body (24) with a uniform inner diameter, and As D1 represents the outer diameter of the rotating shaft (12), D2 represents the internal diameter of the first hole (32), and D3 represents the internal diameter of the second hole (34), Then the outer diameter D1, the inner diameter D2 and the inner diameter D3 satisfy the corresponding relational expressions: D1>D2 and D1>D3>D2. 2. The dynamic shock absorber according to claim 1, wherein a tapered portion (36) is formed between the first hole portion (32) and the second hole portion (34), the tapered portion A portion (36) is located at a position that does not radially overlap said portion of said body (24) on which said strap (20) is fastened. 3. A dynamic shock absorber (50, 50a) for damping vibrations of a rotating shaft (12), the dynamic shock absorber comprising: a generally cylindrical body (52) having a through hole (54) into which said rotating shaft (12) is press fitted; a mass (56) comprising a weight (68), arranged radially outside said body (52); a flexible annular elastic portion (70a, 70b) disposed in said body (52) adjacent to said mass portion (56); and a band (20) fastened to a portion of the outer peripheral surface of said main body (52), thereby securing said main body (52) to said rotation shaft (12), said portion being radially free from all The mass portion (56) overlaps, Wherein, if D1 is used to represent the outer diameter of the rotating shaft (12), and D2 is used to represent the inner diameter of the through hole at an axial end of the main body (52) where the belt (20) is not fastened, and denote by D3 the inner diameter of said through hole (30) at the other axial end of said main body (52) to which said band (20) is fastened, Then the outer diameter D1, the inner diameter D2 and the inner diameter D3 satisfy the corresponding relational expressions: D1>D2 and D1>D3>D2, and the inner diameter D2 is 80% to 85% of the outer diameter D1 %, and the rotating shaft (12) is press-fitted in the through hole from the one axial end having the inner diameter D2 to the other axial end having the inner diameter D3. 4. The dynamic shock absorber according to claim 3, wherein a first hole portion (58) having an inner diameter D2 is formed at one axial end of the through hole (54), ) at the other axial end to form a second hole portion (60) with an inner diameter of D3, and a tapered portion (62) is formed between the first hole portion (58) and the second hole portion (60) , 64), the tapered portion (62, 64) is located at a position that does not overlap with the mass portion (56) in the radial direction and does not overlap with the portion on which the belt (20) is fastened. 5. The dynamic shock absorber according to claim 3, wherein a first hole portion (58) having the inner diameter D2 is formed at one axial end of the through hole, and a first hole portion (58) having the inner diameter D2 is formed at the other end of the through hole A second hole portion (60) having the inner diameter D3 is formed at the axial end, and an R portion having a predetermined radius of curvature is formed between the first hole portion (58) and the second hole portion (60) (78a, 78b), said R portion (78a, 78b) is located at a position which does not radially overlap said mass portion (56) nor overlap said portion on which said strap (20) is fastened.

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